Continuous deep fat fryer



Sept. 27, 1966 J. o. BENSON CONTINUOUS DEEP FAT FRYER 5 Sheets-Sheet 1Original Filed Feb. 14, 1963 FIG. I

INVENTOR.

JOHN O. BENSON ATTORNEY Sept. 27, 1966 J. o. BENSON CONTINUOUS DEEP FATFRYER Original Filed Feb. 14, 1963 5 Sheets-Sheet 2 INVENTOR.

JOHN C. BENSON BY ATTORNEY Sept. 27, 1966 J. o. BENSON CONTINUOUS DEEPFAT FRYER 5 Sheets-Sheet 5 Original Filed Feb. 14, 1963 o o o oUo \.73

Q W INVENTOR.

JOHN o. BENSON BY .DM \a' ATTORNEY Sept. 27, 1966 .1. o. BENSON3,274,920

CONTINUOUS DEEP FAT FRYER Original Filed Feb. 14, 1963 5 Sheets-Sheet 4FIG. l2 FEEDING +5 SUBMERGING L J M 1 Y I83 r184 GIRCULATINGREPLENISHING on. ou.

DISCHARGE PRODUCT INVENTOR JOHN O. BENSON BY M ATTORNEY Sept. 27, 1966J. o. BENSON CONTINUOUS DEEP FAT FRYER Driginal Filed Feb. 14, 1963 5Sheets-Sheet 5 8 IO l2 HOURS- 395! IN FRYER mo o FTP/E ummu r INVENTOR.

JOHN O. BENSON FIG. II

ATTORNEY United States Patent 3 Claims. (61. 99-404) This application isa division of application Serial No. 258,577, filed February 14, 1963.

This invention relates to an apparatus for deep fat frying foodproducts, and more particularly to an apparatus for continuously deepfat frying cereal products in cooking oil with a minimum accumulation ofundesirable contaminants.

Satisfactory, deep fat frying of various food products such as cerealproducts requires close heat control. Close control of the temperatureof the cooking oil must be maintained in order to properly cook theproduct without undue absorption of oil by the product and to cook theproduct without burning or otherwise damaging the product beingprocessed. The proper control of the temperature of the cooking oil isin some measure dependent upon the circulation of the oil about theproduct and about the heating coils utilized to heat the oil. Manyfryers which are more or less satisfactory utilize only convectioncurrents set up by the heated oil for circulation purposes. Howeverthese convection currents often produce insufiicient circulation of thecooking fat or oil about the heating coils and consequently result indamage to the oil itself. Poor circulation of the oil and localoverheating of the oil near the hot wall or heating element of a heaterresults in the accumulations of high concentrations of constituents suchas free fatty acids. Normally it is desirable to maintain the free fattyacid concentration or the concentration of other elements at apredetermined level in the cooking oil in order to produce a finishedproduct which can be stored for an extended period of time without achange of the flavor.

Poor quality control for the cooked product results if the temperatureof the oil and the constituents of the oil cannot be controlled to arather precise degree. Imprecise control of the time the product iscooked, often results in an additional contribution to the breakdown ofthe oil which in turn results in an unusually frequent need to replacethe entire bulk of the oil in the system.

imprecise control of the temperature of the oil, the circulation about aheater and the cooking time for the product when it is in contact withthe oil results in an acceleration of the breakdown of the oil. In theusual system this rapid breakdown of the oil results in an interruptionof the frying process since the entire volume of the frying oil must bedrained from the system and replaced with fresh oil before the fryingoperation can continue.

It is therefore an object of the present invention to provide a new andimproved apparatus for continuously deep fat frying food products.

It is another object of the present invention to provide a new andimproved apparatus for continuously deep fat frying food products undercontrolled conditions to prevent the accumulation of undersirableconstituents in the cooking oil.

It is yet another object of the present invention to provide a new andimproved apparatus for continuously deep fat frying a food product inthe cooking oil which is continuously circulated, heated, andreplenished to maintain the free fatty acid concentration of the oil ata low and constant level for an extended period of time.

It is another object of the present invention to provide a new andimproved apparatus which is capable of continuous operation in whichthere is employed a small quantity of cooking oil or fat relative to thevolume of food immersed therein at any one time and which oil isreplaced on a periodic basis to maintain the undersirable constituentsof the oil at a minimum level.

A complete understanding of the invention may be obtained from thefollowing detailed description of an apparatus forming specificembodiments, when read in conjunction with the drawings, in which;

FIGURE 1 is a front view of an apparatus according to the invention,

FIGURE 2 is a top view of the apparatus shown in FIGURE 1,

FIGURE 3 is a left end view in FIGURE 1,

FIGURE 4 is an enlarged view of a material meter, partly in crosssection, which is disclosed in FIGURE 3,

FIGURE 5 is a cross section of a heater utilized for heating oil to acooking temperature,

FIGURE 6 is a back view of a bucket utilized to contain the foodproduct,

FIGURE 7 is a right side view of the bucket shown in FIGURE 6,

FIGURE 8 is a cross sectional 88 of FIGURE 7,

FIGURE 9 is a cross sectional 9-9 of FIGURE 4,

FIGURE 10 is a circuit diagram showing the circuitry utilized to controlsome of the valves which coordinate the operations of the apparatus,

FIGURE 11 is a graph showing percent free fatty acid product againsthours of cooking time for a batch type fryer and a continuous fryer, and

FIGURE 12 is a flow diagram showing the continuous cooking of a foodproduct.

Refer first to FIGURE 1 of the drawings, FIGURE 1 is a front view of themachine according to the present invention showing the tank 21 which isutilized to contain frying oil such as safflower oil, corn oil, coconutoil, and the like. In order to provide a container which is adequatelylarge to accommodate a Ferris wheel type product supply system, thecontainer 21 is shaped basically in the form of a semicircle. At thebottom of the tank or container 21 is an outlet or drain 22 fordischarging any accumulations of product or the like which might settleto the bottom of the tank. The drain 22 is also utilized to drain theentire tank when the apparatus is not in use. A top View of the tank 21is shown in FIG- URE 2 of the drawings. It is noted there that the tankor container 21 is .generally rectangular in shape. The container 21 isrelatively narrow from front to back in order to provide a minimum oftank volume. It is only large enough to accommodate the Ferris wheeltype material supply system. This optimum tank size is utilized in orderto provide adequate oil for completely submerging the product and at thesame time maintain a minimum of hot oil exposed to the atmosphere.Exposure to the atmosphere reduces the quality of the oil by oxidationand results in a need to replace the cooking oil on a less frequentbasis. Consequently, the tank or container 21 is shaped as described tomaintain the oil in the fryer in as good condition as possible for aneX- tended period of time.

The tank is mounted on a chassis 27 which provides the supportingstructure for all of the elements of the apparatus. The container 21 isbolted to the chassis 27 or connected to the chassis 27 in some othersuitable manner such as welding.

A Ferris wheel type product supply generally designated by the numeral28 is mounted at the rear or near the rear wall 24 of the container 21.The Ferris Wheel type product supply 28 has a number of arms 29. Thoseof the apparatus shown view taken along line view taken along lineradially extending arms 29 are monuted on a hub 31 which is connected toa drive shaft 32. The drive shaft 32 is connected to the chassis 27 by abearing block 33. Opposite the hub 31, is a sprocket 34 which is engagedby a sprocket chain 36. Sprocket chain 36 and sprocket 34 are driven bya variable speed drive motor 37 which is connected to the drive sprocket34 by a gear reducer system 38 and a sprocket and chain system.generally designated by the numeral 39.

The motor 37 is connected by a clutch 41 to the gear reducer 38. Thegear reducer 38 is utilized to set the operational speed of rotation ofsprocket 42 and the connected sprocket 34. This in turn regulates thespeed of rotation of the Ferris wheel 28. This rotation is regulated totime the movement of the Ferris wheel 28 with other parts and operationsof the continuous fryer.

Thus it can be seen that the gear reducer system 38 permits a precisecontrol of the rate of rotation of the Ferris wheel 28 which carriesbaskets or buckets 46. Additionally with this precise control of therate of rotation of the Ferris wheel 28 and the use of optimum containersize 21 which contains oil or cooking fat, it is possible to closelyregulate the relationship between the volume of product which isintroduced into the container 21 for a given period of time in relationto the amount of oil which is contained in the entire system includingthe container 21. This precise regulation of the amount of productintroduced into the oil and a use of minimum oil in the system resultsin a control of contaminants which are introduced into the oil. Thiscontrol permits maintenance of a high quality of cooking oil for acontinuous frying operation.

At the end of each of the radially extending arms 29 of the Ferris wheel28, a bucket 46 is pivotally attached. These buckets carry the foodproducts, such as a cereal product, into and out of the oil in the deepfat fryer. The buckets 46 are perforated buckets designed to carry theproduct into and submerge the product in the frying oil.

Refer to FIGURES 6 and 7 for enlarged detailed views of the buckets 46.Lugs 47 are utilized to pivotally connect the basket or bucket 46 to thearms 29 of the Ferris wheel. The lug 47 contains an aperture 48 which isdesigned to receive a projection or shaft 49 of the arm 29. Thisprojection or pivotal shaft 49 is inserted within the aperture 48. Eachprojection 49 contains a slot 51 near one end of the projection 49. Thisslot 51 engages a pin 52 which is inserted within the opening 48 throughan aperture 53 in lug 47. The pin 52 is spring biased by a spring 54 sothat the pin 52 engages the slot 51 to lock the projection 49 into thelug 47. One end of the spring 54 rests against a retainer pin 56 and theother end rests on a shoulder in aperture 53. Thus when the projection49 is inserted within the aperture 48 the arm 29 of the Ferris wheel ispermanently and pivotally attached to the bucket 46. The lug 4-7 is inturn connected to the sidewall 57 of the bucket 46.

Refer now to FIGURE 7 of the drawings. A cam follower 58 is bolted orotherwise connected by suitable means to a slide 59. A portion 54) ofthe mounting lug 47 projects into a slot 61 of the slide 59 (refer toFIGURE 6). The projecting portion 56 of the lug 47 vertically guides theslide 59 when it is moved from an upper position shown by the solidlines in FIGURE 7 to a lower position illustrated by the dotted lines inFIGURE 7.

Opposite the slide 59, a rod 62 is attached to the cam follower 58. Thisrod 62 engages an aperture 63 in the lug 47. Rod 62 is a guide whichprovides a means for guiding the cam follower 58 when the follower ismoved vertically by a caming surface 64 which is shown in FIG- URE 1 ofthe drawings. Follower 58 is a tapered roller which is mounted forrotation about a horizontal axis as viewed in FIGURE 7.

Opposite the cam follwer 58, a T-bar 66 is connected to the slide 59 sothat the leg of the T-bar 66 engages the slide 59. A bracket is fittedto the leg of the T-bar 66 and captures a compressible coil spring 68between the bracket 67 and the slide 59. The bracket 67 is connectedpermanently to the back surface 69 of the basket 46 so that the coilspring 68 is compressed when a cam such as cam 64 shown in FIGURE 1,forces the cam follower 58 and slide 59 vertically downward as viewed inFIGURE 6. The spring 68 is captured between the bracket 67 and a flaredportion 71 of the slide 59 at a point where the leg of the T-bar isattached to the slide 59.

The arms 72 of the T-bar 66 are attached to gates 73 of the container46. Gates 73 are pivotally connected by a hinge type joint 74 to thebody of the container 46. The hinge 74 extends across the entire side ofthe container 46 as shown in FIGURE 7 of the drawings.

The gates 73 are each designed to cover half of the bottom 76 of thecontainer 46 in order to trap food products such as flakes or grains ofcereals in the container 46 during the frying operation. The gates 73may or may not be perforated depending upon the characteristics of theproduct and the amount of oil circulation which is needed about theproduct while the cooking or frying is taking place.

The gates 73 are opened for discharge of the product as shown by thedotted lines in FIGURE 6 of the draw ings. The arms 72 of the T-bar 66are attached to the extended. sides 77 of the gates 73. A bolt or rivet78 engages a slot '79 in each of the arms 72 so that the gates 73 may beeasily opened by vertical downward movement of the T-bar 66. When thecam follower 58 engages the cam 64, the follower 58, slot 59, and rod 62are forced vertically downward as viewed in FIGURE 6. The springcaptured between the flared portion 71 and the bracket 67 is compressedand the T-bar 66 is displaced to the dotted position shown in FIGURE 6.When the T-bar 66 is thus displaced, the arms 72 of the T-bar force thegates 73 open as shown in the dotted lines in FIGURE 6. Any productwhich might be contained in the container 46 is then discharged as aresult of the opening of gates 73. When the cam 64 disengages the camfollower 58, the

compressed coil spring 68 forces the cam follower, the

slide 59 and the T-bar 66 vertically upward and thus closes the gates 73so that the container 46 can again be charged with product for anothercooking cycle.

The bucket 46 is provided with a hinged lid 81. This lid is used toprevent the food product from floating out of the bucket 46 when thebucket is completely submerged in the hot cooking oil. The lid 81 may beperforated to permit free circulation of the oil through the bucket tohelp insure uniform frying of the food product.

The lid 81 is connected to the bucket 46 by a hinge 82. An extension 83of the lid 81 extends beyond the hinge 32 and is utilized to open lid 81in cooperation with the rod 62. When the cam follower 58 is displaced bycam 64, the rod 62 engages the extension 83. The extension 83 isdisplaced by rod 62 to the dotted position illustrated in FIGURE 7, thuspivoting the lid 81 open. The lid remains open until after the bucket 46is recharged with food product.

When the gates 73 of the buckets 46 are opened, the cooked product isdischarged. However, very often some cooked products will tend to clingto the sides of the bucket 46 or to the inside surface of the gate 73.If this cooked food product should remain in the buckets 46 after thegates are closed and the bucket is recharged, the already cooked productwould again be fried. This second frying of the food product will burnthe product. Discharge of this burnt or overcooked product tends toreduce the overall uniformity and quality of the product and isundesirable. Consequently, an air discharge assist is utilized to insurecomplete discharge of all food products from the bucket 46. A nozzle 91is mounted on the frame or chassis 27 of the machine (see FIGURE 1). Thenozzle 91 is located so that the gates 73 and the lid '81 are openbefore the nozzle discharges air. This location is illustrated in FIGURE1 of the drawings where the bucket 46 is shown in the uppermost positionwith the gates 73 opened and the lid 81 opened by the cooperation of thecam 64 and the cam follower 58.

A nozzle 91 is connected through a conduit 92 to an air pump 93 whichsupplies air to the nozzle 91 at a discharge pressure adequate todislodge any food product which may cling to the sides or bottom of thebucket 46. A motor 94 is utilized to drive the air pump. The airdischarged from the nozzle 91 must be controlled so that the air isdischarged from the nozzle 9-1 only when a bucket 46 is in position asshown in FIGURE 1 with the gates 73 and lid 81 opened. A valve 96 isplaced in the line 92 to control the air flow in the line 92. Valve 96is a solenoid valve or any other type of-valve which may be controlledto periodically open and close the line 92.

A gear-type timing device is utilized to accomplish the periodic openingand closing of the valve 96. Refer now to FIGURE 3 of the drawings. Atiming system generally designated by the numeral 97 is connected to thegear reducer 3 8. The timing system 97 is a chain and sprocketarrangement having a drive sprocket 9 8 connected to a timing sprocket99. The sprocket 99 is connected to a shaft 101 which is mounted on thechassis by hearing blocks 102. The shaft 101 carries a cam 103 whichrotates with the shaft 101 and engages an extended arm 104 of a microswitch 106. As previously noted, the Ferris wheel 28 is timed throughthe gear reducer 38. This same gear reducer 38 is also utilized to timethe rotational shaft 101 so that the cam 103 engages the microswitch 106each time a bucket 46 is in the uppermost position or discharge positionas shown in FIGURE 1 of the drawings.

When the arm 104 of microswitch 106 is actuated, the microswitch 106closes an electrical circuit to energize a solenoid 100 associated withthe solenoid operated valve 96. Refer to FIGURE of the drawings. Themicroswitch 106 is shown with the cam 103. When the switch 106 isclosed, the power source 107 is placed across the solenoid 108. Solenoid108 opens the solenoid operated valve 96 and permits air to pass fromthe line 92 to the nozzle 91. Thus the discharge of air from nozzle 91is precisely timed with the arrival of the bucket 46 at the dischargeposition. The blast of air which occurs from the nozzle 91 purges thebucket 46 of all of the fired prodnot so that it is discharged into adischarge chute 108. The microswitch 106 is only momentarily operated bythe cam 103 and as soon as the shaft 101 is rotated through apredetermined arc, the microswitch 106 is again returned to its openedposition as shown in FIGURE 10. The solenoid valve 96 is then againclosed and the air flow from the nozzle 91 is terminated.

After the bucket 46 has been purged of cooked food product, the Ferriswheel 20 is rotated in the counterclockwise direction as viewed inFIGURE 1 to a position which is shown in dotted lines. In this position,the bucket 46 is situated under a charging chute 109. As the bucket 46is rotated in the counterclockwise direction by the Ferris wheel 28, thecam follower 58 disengages the cam 64 and the spring 68 mounted on theT-bar 66 returns the cam follower 58, T-bar 66 and gates 73 to theclosed position so that food products may be trapped in the bucket 46.

The bucket 46 is charged with a measured quantity of food product. Thebucket must be charged With a known quantity of the product so thatprecise control of the amount of product immersed in the oil over agiven period of time may be accurately controlled. This precise controlof the amount of product which is immersed and fried in the oil acidscontrol of the quality of the oil as measured by the concentration offree fatty acids which accumulate in the oil when it deteriorates.

In order to accomplish the precise control of products place-d inthebucket 46, a metering chamber '111 is utilized to charge the buckets 46.Refer now to FIG- URES 3, 4, and 9. The product is introduced into themetering chamber 111 through a chute 11 2. The product from chute 112 istrapped in a chamber 113 which is formed by the beveled side walls 114of the metering chamber .111 and an interior retaining wall 116. Theretaining wall 116 extends across the metering chamber 11 1 from side toside but contains an opening 119 between the top surface 117 of the wall(see FIG. 9) and the inside surface 118 of the metering chamber 111.This opening 119 permits the food product to flow into a second chamber121 of the metering chamber 111. The chamber 121 contains an opening:122 for discharging the product from the metering chamber 111 when themetering chamber has been rotated by the indexing system 97.

The metering chamber 11 1 is mounted on shaft 101 of the indexing system97. The clockwise rotation of the metering chamber 111 is timed so thateach time a bucket 46 is rotated to the position shown by the dotedlines in FIGURE 1, the metering chamber 111 is rotated so that thedischarge opening 122 is at the bottom of the chamber as viewed inFIGURE 3. Consequently, the food product which is contained in thechamber 113 is discharged through the opening 119 to the chamber 121where it is further discharged into the bucket 46 through opening 122.The discharged product flows from the chamber 121 into the chute 109 andinto the bucket 46.

The bucket lid 81 which was previously opened by the rod 62 is nowmaintained in an opened position by engagement with the chute 109. Chute.109 prevents closure of the lid 81 until after the product has enteredthe bucket 46 and the bucket has moved out of engagement with the chute109. After the bucket 46 is further rotated in the counterclockwisedirection out of engagement with the chute 109, the lid 81 which is nolonger engaged by the rod 62, will close and cover the food product inthe bucket 46. Closure of the lid 81 prepares the bucket for submersionin the oil. The lid 81 prevents the product which is to be fried in theoil from floating out of the bucket 46 as the food product and bucketare completely immersed in the oil for the frying operation.

After the bucket 46 has been charged, the shaft v101 continues to rotatethe chamber 111 so that the opening 122 is no longer in a position todischarge products. New products continue to enter the chamber 113 inpreparation for a new charging cycle which will take place with the nextsucceeding bucket brought into alignment with the chute 109. The productis continuously fed to the metering chamber 111 but the wall 116 and theconfiguration of the chamber 111 permits measured quantities of thematerial to be deposited in the bucket 46. The wall 116 interrupts theflow of the material when no bucket 46 is aligned with opening 122. Aprojection 123 extended along one side of opening 1-22 to help controlthe discharge of the material through opening 122..

The gear reducer 38 is selected so that it will drive the Ferris wheel20 at desired speed. Either the gear reducer itself may be selected toincrease or reduce the speed of rotation of the Ferris wheel 28 or thesprocket and chain arrangement which drives the shaft 32 may be selectedto adjust the rotational speed of the Ferris wheel 20. As an example,the rotational speed of the Ferris wheel can be adjusted so that theproduct is submerged in the oil for as little as 5 seconds to as long as50 seconds. This period of time, depending upon the temperature of theoil and other factors, is normally adequate to fry the food productwhich is contained in the bucket 46. The movement of the Ferris Wheel 28carries the bucket 46 from the initial immersion of the bucket andproduct in the oil, into the tank or container 1211, till it finallyemerges from the oil a predetermined time after entrance of the bucketinto the oil. The product, after removal from the oil, is uniformlycooked to a satisfactory degree and is then discharged from the bucket46 at a discharge station where the product engages chute 108. Thus acomplete cycle of the cooking operation has been completed by thecontinuous deep fat fryer.

Oil is supplied to the tank or container 21 by an oil supply andcirculating system in order to further achieve continuous operation ofthe frying apparatus for extended periods of time without undue orexcessive deterioration of the cooking oil. As has been previouslynoted, the container 21 is so shaped that the Ferris wheel 28 with theattached buckets 46 fit with a minimum of wasted volume within thecontainer 21. This use of a minimum volume for the container 21 resultsin a need for a minimum volume of oil in the container 211 for thefrying operation. The reason for maintaining this container 21 at aminimum volume and in a shape adequate only to admit the Ferris wheeltype supply system is to reduce the surface area of the oil which isexposed to the atmosphere. Exposure of hot cooking oils to an oxygenladen atmosphere results in oxidation of the hot oil. Oxidation of theoil results in a breakdown of the oil and reduction of the quality ofthe oil. Additionally, the reduced volume of the container 21 reducesthe amount of oil which must be heated to elevated frying temperaturesin order to achieve satisfactory frying of the product. Exposure of theoil to the atmosphere at these elevated frying temperatures tends tocontribute to the breakdown of the cooking oil. Thus a reduction of thequantity of oil which is heated to the [frying temperatures reduces thequantity of oil which is subject of deterioration or breakdown inquality.

Due to the inherent nature of deep fat frying operations, however, acomplete elimination of the oxidation of oil or deterioration of oil dueto elevated frying temperatures cannot be completely eliminated.However, its effect may be reduced to a minimum. An oil supply system isprovided for the apparatus which is capable of maintaining precisecontrol of the circulation of the oil in the entire system. Provision isalso made to maintain the oil level in the container 21 at a preciselevel. The control of the circulation and level helps reduce to aminimum the exposure of the oil to the atmosphere and reduces exposureof a given volume of oil, for extended periods of time, to excessive hotwall temperatures in the remote heater utilized in the system.Additionally, the remote heater directly heats the oil in order toreduce the hot wall temperatures and in order to help maintain a lowconcentration of contamination in the oil.

Refer now to FIGURE of the drawings which shOWs a heater for directlyheating the cooking oil. Oil enters the heater 137 through line 132. Theoil is heated in the heater 137 by an electrical coil 163 which is indirect contact with the frying oil. This direct contact of the heatercoils 186 with the frying oil permits a minimum temperature of theheating coils .133 in order to heat the oil to a satisfactorytemperature. This maintenance of the heating coil-s 183 of the heater ata minimum temperature necessary to attain the frying temperature resultsin an extension of the period of time the oil may the used beforeaccumulations of contaminant requires its removal. Heat is transferredmore readily from the coils 133 to the oil in this system than in aheating system where several heat transfers must take place before theoil is heated. In this case the heating coils 133 are low amperageheating coils.

The heated oil then rises to the top of the tank 131 and exits throughline 136 where it flows to the container 21. Experience with this typeof heater has shown that the hot wall temperature may be maintained aslow as from about 390 F. to 500 F. and yet the fying oil will be heatedto a frying temperature of from about 330 F. to about 420 F.

After the oil has been properly heated in the heater 137, it isdischarged through a line 136 which interconnects the heater 137 and thecontainer 21. The heated oil flows into the container 21 due to thepumping action of a pump 140 which is driven by a motor 138. The motor138 and pump 140 may be a system which provides a constant volume offlow of the oil throughout the system. This constant flow pump permitsthe use of valves for regulating the rate of flow of oil in the system.In other words, if an increase in the oil flow is desired, then a valvemay merely be opened or closed in order to increase or decrease the flowof the oil in the system.

The hot frying oil is discharged into the container 21 where the Ferriswheel 28 carries the product laden buckets 46 into the heated oil. Theproduct is cooked to a desired degree by the hot oil and is then removedfrom the oil by the Ferris wheel system. The oil is then pumped out ofthe container 21 through line 139 and is returned to the heatingcomponents of the system.

Refer now to FIGURES 3 of the drawings. The cooled oil travels from thecontainer 21 through a line 139 and is directed into a filter 141. Asmight be expected small particles of the food product escape from thebuckets 46 through the perforations in the walls and bottom of thebucket.

These small particles tend to flow with the oil throughout the system.Consequently, some means is needed to remove these particles from thecirculating oil in order to prevent plugging of the various lines andcomponents of the heating and circulating system. The filter 141 filtersthese suspended particles and cleans the oil before it is returned tothe pump through line 142.

The pump 140 then forces the oil through line 143 into a rate of flowmeter 144. The rate of flow meter is used in system to maintain aconstant check on the rate of flow of the oil throughout the system. Arather constant, uniform, and high rate of flow is utilized in thesystem in order to return the oil to the heater 137 often enough toprevent high losses of heat energy in the oil. This conservation of theheat in the circulating oil reduces the need for high heater elementtemperatures in order to restore the cooled oil to a frying temperature.This reduction in the heater element temperatures necessary to returnthe oils to the frying temperature, reduces deterioration of the oil dueto high temperatures. The rapid circulation of the oil also has atendency to maintain the oil in a particle free or cleaned condition sothat the oil remains of high quality for extended periods of time.Maintenance of the oil quality for extended periods of time is adesirable feature in a continuous fryer such as this one.

Any number of commercial devices may be used as a rate of flowindicator. One such device is an Armet Rotometer No. 36 11. The meter144 contains an electrical system 146. When an undesirable flow rateoccurs in the system, a signal is generated and is amplified. Theelectrical system 146 contains a contact means which is responsive tothe amplified signal. This switch is connected to the conventional servosystem by contacts 147. The servo system is not shown, however, it is aconventional system which interconnects the contacts 147 and a servomotor 148. The servo system may be designed so that the motor 148 opensand closes a valve 149 in accordance with a signal which is receivedfrom the flow meter 144. The signal indicates the rate of flow whethergreater than an optimum value or less than an optimum value. Dependingupon the variation of the oil flow from the optimum value, the motor 148operates the valve 149 to increase or decrease the flow of oil throughthe system.

The rate of fiow in the system may be adjusted depending upon theparticular operating characteristics of the fryer. For instance, if arelatively quantity of suspended particles is captured in the oilcirculating in the system a higher rate of flow may be necessary tomaintain the oil in a relatively clean condition. Also, the rate of flowmay be adjusted in accordance with the characteristic heat losses of thesystem in order to maintain a certain temperature of the cooled oil whenit returns to the heater 137. This rate of flow, however,

will have to be adjusted in accordance with the heat losscharacteristics of the circulatory system and will naturally vary frommachine to machine depending upon the type of conduit or lines used, thetype of filter used, the volume of the system, the distance between theheater 137 and the container 211, and other similar physicalconsiderations.

After the oil passes through the flow meter 144 it is returned via line132 to the heater 137. The oil is then again heated by the heatingelements 133 and it is again discharged through the line 136 where it isused to fry food products.

In a continuous deep fat fryer such as this one, where a minimum volumeof oil is utilized to fry the food product, a precise control of thelevel of oil in the container 21 is desirable. A control is necessaryfor several reasons. First of all, deep fat fried products normallyabsorb a great deal of fat. The finished or cooked product may, forinstance have a concentration of from 30 to 60% fat. Most of this fat ispicked up in the deep fat fryer during the frying operation. If arelatively large volume of product is being fried in a fryer having aminimum volume of oil, the removal of the frying oil becomes quiteappreciable. The removal of the frying oil at a relatively rapid rate,however is utilized in this continuous deep fat fryer in order tomaintain a high quality of oil for an extended period of cooking time.

In order to regulate the level of oil in the container 21, a surge tank151 is connected into the line 139. New oil from tank 152 is introducedinto the surge tank 151 through a line 153 in accordance with theremoval of the oil from the container 21 by the product. The surge tank151 is situated behind the container 21 and is tied into the container21 so that the level of the oil in the surge tank 151 is the same as thelevel of the oil in the container 21 during the cooking operation. Afluid level control 154 is mounted in the wall of the surge tank 151.The level control may be a commercial item such as that manufactured byH. Fielden & Company, No. ME 4. The control level has a pair of contacts156 and 157 for sensing the level of the oil in the surge tank 151.Refer to FIGURES 3 and 10. The contacts 156 and 157 are verticallyspaced from each other so that the upper contact 156 determines theupper limit of the oil level in the container 21 and surge tank 151 andthe lower contacts 157 determines or sets the lower level of the oil inthe container and tank. The level of the container and surge tank willvary depending upon the distance between the contacts 156 and 157. If avery small variation in level is desired, the contacts are placed closetogether to reduce the variation of the oil level.

The level control 154 contains a contact, now shown, which closes anelectrical circuit across source 107 (see FIGURE 10). Closure of theswitch in the level control 154 energizes the winding 158 of solenoid159. Solenoid 159 controls the hydraulic valve 161 to open and close thevalve. Valve 161 controls the amount of new liquid which is permitted toflow into the surge tank 151 through line 153. If, for example, theliquid level in the surge tank 151 falls below the contact 157, a signalis generated which closes a switch in the level control 154. Thesolenoid 159 is energized by the source 107 which opens the valve 161.Liquid flows from the container 152 into the surge tank 151 until theliquid level in the surge tank touches the upper contact 156. When uppercontact 156 senses the oil, the control 154 opens the line across thesource 107 to de-energize the solenoid 159 and return it to the closedposition. Thus the valve 161 is closed and the flow of oil into thesurge tank 151 is terminated. Additional new oil is not introduced intothe surge tank 151 until contact 157 again senses the oil level of thesurge tank. Since the volume of oil contained in the system isrelatively small as compared with the amount of product cooked in thecontinuous fryer over a given period of time, the introduction of newoil into the surge tank 151 occurs 10 on a nearly constant basis. Thefried food product such as a cereal, removes the oil at a constant andrapid rate. This removal of the oil at a rapid rate results in a flow ofnew oil into the surge tank 151 and into the system on a relativelyconstant basis.

In order to maintain the oil in the system in good condition with a lowfree fatty acid concentration, a high replacement rate is desirable.Replacing the entire volume of the oil in the system at least once inabout every three to four hours is the least frequent replacement ratewhich will maintain the oil in an overall high quality condition.Consequently, the rate of rotation of the Ferris wheel 28 and thequantity of material placed in the buckets 46 by the meter 111 isadjusted so that the product removes the entire volume of the oil in thesystem in about three to four hours. If the product absorbs or carriesaway a very small amount of oil, the volume of the oil in the systemmust be reduced in order to attain this optimum removal rate. The volumein the system may be reduced by simply reducing the size of thecomponents in the system.

On the other hand, if the product removes a high volume of oil, theproblem is somewhat less to maintain an exchange of the oil at least ona three hour basis. The product which removes a higher percentage of theoil may actually remove a volume which will result in a need to replacethe oil more frequently than on a three hour basis. This does notrequire an adjustment of the com ponents or volume of the system since amore frequent replacement of the volume of oil in the system has beenfound to maintain the oil in good condition with a very low free fattyacid concentration.- Theoretically, the most desirable replacement rateof the oil is instantaneous. Thus new oil would be present in the systemat all times. As a practical matter however, it is not possible ordesirable to use fresh oil at all times. Consequently, as noted, it hasbeen found that if the oil is replaced on a volumetric basis at leastevery three hours, the free fatty acid concentration which is being usedas the basis for measuring the quality of the oil, will remain at aconstant level which is very acceptable for deep fat frying a foodproduct such as cereal.

Refer next to FIGURE 11 of the drawings where there is shown a graphwhere the percent of free fatty acid in the cooking oil is plottedagainst the number of hours of operation of the particular machinesinvolved. Curves 1'71 and 172 are compiled from data taken in connectionwith the operation of a batch fryer which is a commercially availableunit commonly used in the deep fat frying industry. Curves 173 and 174are curves constructed from data taken during the operation of thecontinuous deep fat fryer which is the subject matter of thisapplication. In each instance the temperature of the frying oil which isin the frying container was maintained at 395 F. The oil used to compilethe data was new coconut oil which had a FFA concentration of about.02%. Often, however, new oil will have a free fatty acid concentrationof from about .0170 to .04%.

The percentage of free fatty acid concentration in the oil was selectedas a measure of the quality of the frying oil. Free fatty acid iscommonly used in the deep frying industry which includes cerealproduction and potato chip production, to indicate the quality of theoil after it has been used in a deep fat frying operation. Free fattyacid content, as the term is used herein, is determined by titration ofa sample dissolved in a ethanol solution with a 0.1 sodium hydroxide toa phenolphthalein end point.

Curve 71 is a test of the quality of the frying oil in the batch fryeras measured by the percent of free fatty acids present in the oil, overa period of 25 hours operation. The oil was maintained at 395 F. for theentire period but no product was fried. It should be noted that thepercentage of free fatty acid increased rather sharply throughout the 25hours of operation. Next the batch fryer was recharged with fresh oiland a cereal product was fried in the oil in the usual manner ofoperation of the batch fryer. Tests were made of the percent free fattyacids present in the oil over a period of 25 hours of operation. Theresults of this data is illustrated by the curve 172 in FIGURE 11. Hereagain the concentration of the free fatty acids in the frying oil isnoted to rise very sharply and continue to rise at varying rates overthe entire 25 hours of operation. The batch fryer is of the type inwhich oil is replaced on a periodic but not a continuous basis when oilis needed. It is noted that the concentration of the free fatty acidrapidly exceeds the commonly used discard specification of 0.5% freefatty acids. When no product is being cooked, the .5 value is exceededafter approximately four hours of operation. This same discardspecification of .5% is exceeded in about 8 hours when product isactually cooked in the fryer. After exceeding the .5 value, theconcentration of free fatty acids continued to increase rapidly beyondacceptable limits.

Next the continuous deep fat fryer according to this invention wascharged with fresh coconut oil and the oil was heated to a temperatureof 395 F. The circulatory system was started and the heater wasconnected to automatically maintain a temperature of 395 F. No productwas fried when this data was gathered. Periodic tests of theconcentration of free fatty acids in the oil were taken and curve 173 isthe result of the gathered data. It is noted that the curve 173 isnearly a flat curve. Even at the end of 25 hours of operation at thenoted temperature, the free fatty acid concentration in the oil was wellbelow the .5% free fatty acid which is commonly regarded as the discardpoint for the oil. Next the continuous deep fat fryer was charged with afresh batch of coconut oil and a cereal product like that used in thebatch fryer was fried in the fryer continuously for 25 hours. It isnoted when the product is being cooked in the fryer, that the free fattyacid concentration rises to about the .07% free fatty acid level anddoes not increase beyond that point for the entire 25 hour period ofcooking. This FFA level may be somewhere nearer .1% if the new oilcontains a higher FFA concentration. This virtually flat curve 174indicates that the concentration of the free fatty acid in the oilremains constant for an extended period of time, well below the accepteddiscard specification of .5 free fatty acid concentration in a fryingoil. The test data for curve 174 was gathered while the oil in thecontinuous fryer was being replaced on a volumetric basis about onceevery three hours. As previously indicated a more rapid volumetricreplacement rate of the frying oil in the continuous deep fat fryer willresult in at least as satisfactory results as that indicated by thecurve \174.

This constant concentration of free fatty acid which is established inthe oil after about 6 hours of cooking, permits deep fat frying ofvarious food products with a high degree of quality control of theproduct. The concentrations of free fatty acid which are believed toaffect the flavor of the product are precisely none when fried in thecontinuous deep fat fryer. Consequently, a precise and uniform flavorcan be established in a food product because of the small variation ofthe free fatty acid concentration over an extended period of time.

Any number of food products may be cooked in the continuous deep fatfryer. In the above data, the product which was used was a cerealproduct composed primarily of corn flour with a small amount of oatflour. Other cereals such as wheat, rice and combinations of the variouscereals may be formed into a dough type product and may be cooked in thedeep fat fryer. It should be noted however, that whole grain cereals maybe fried in the deep fat fryer with a proper adjustment of thetemperature and other adjustable factors. It is also to be noted thatthe above list of cereal products is not to be deemed as limiting on thetypes of products which may be utilized in the continuous fryer nor arethe products to be deemed as limiting or the process of cooking a foodproduct as is set forth hereinafter.

It is to be understood that the above described continuous deep fatfryer may be used on a number of food products. A specific example,however, of the continuous deep fat frying of a cereal product involvesthe following:

Percent Corn flour 75.3 Oat flour 10 Sugar 6.3 Salt 3.1 Starch 5.3

The above mixture of cereal products is then formed in a dough andpellatized before it is placed in the meter 111. The temperature of theoil in the fryer is adjusted so that the oil in the container 21 is fromabout 330 F. to about 420 F. The rotation of the Ferris wheel 28 isadjusted so that the time that the product is submerged in the oil ofthe container 21 varies from about 5 to about 50 seconds depending uponthe particular taste characteristics which are desired for the finalproduct, the nature of the product itself, and the precise temperatureswhich is chosen as the operating temperature.

Refer now to FIGURE 12 of the drawings which shows a flow diagram of aprocess utilize-d in connection with the above described continuousfryer to cook, the cereal product. The product is fed into the meter 111of the apparatus. The meter 111 then dumps the predetermined amount ofproduct into a bucket 46 which is being rotated by the Ferris wheel 28at a predetermined rate. This processing step is represented by box 181of the drawings. Next the cereal product is carried by the buckets 46into the oil in the container 21. Here the product is cooked in the hotfrying oil for a predetermined time as determined by the rate ofrotation of the Ferris wheel 28. The product may or may not be submergedin the oil of the container 21. However, complete submersion of theproduct is preferable since it prevents the product from floating to thesurface of the oil where uneven and uncontrolled rates of cooking maytake place in the product. If the product is not completely submerged inthe oil, the product may remain partially uncooked and result in afinished product which is not uniform in quality. The lid of the bucket46 insures that the product may be completely submerged in a preferredmethod of cooking the product. This submersion of the product in thecooking oil is represented by box 182 which illustrates an alternatemethod of treating the product. In other words the feeding of theproduct into the oil may not involve the step of completely submergingthe product. However, a preferred method does include completesubmersion of the product.

Prior to and during the frying of the product in the oil, the oilcirculating system which includes the pump is actuated to circulate theoil through the tank 21, the filter, the heater, and the variousconduits of the system. The circulating oil contacts and uniformly firesthe product. As noted previously, this circulation insures a highquality of the heating oil by reducing the breakdown of oil as a resultof high heating temperatures in the filament of the heater. It also aidsremoval, on a rather frequent basis, of products which may be dischargedinto the oil from the buckets 46. These products also as noted have atendency to clog the system and interfere with free circulation as wellas reduce the overall quality of the oil by the suspension of a numberof overcooked particles in the oil. As noted in connection with box 183of the flow diagram, the circulated oil is heated to a fryingtemperature depending upon the product and other factors as notedherein.

Simultaneously with the feeding of the product, submersion of a productin the frying oil and circulation of the oil; fresh oil is continuouslyintroduced into the deep fat fryer in order to replace the oil removedby the cooked product and also to aid maintenance of the overall highquality of the oil circulated in the system. As noted with box 184 ofthe flow diagram, the oil is replenished simultaneously with thecirculating, heating, submerging, and feeding of the product. Thereplenishment of the oil is accomplished in the continuous fryer by alevel control which was described in connection with the surge tank. Thelevel control regulates a valve interconnecting a source of new oil andthe surge tank. The valve is opened or closed in accordance with thelevel of the oil in the container 21. Ideally this replenishment of theoil should take place on a nearly constant basis. Constant replacementof the oil help maintain a constant low concentration of free fatty acidin the oil used to fry the product. Replacement of oil on a batch basistends to result in a build-up of the free fatty acids and consequentlyresults in a non-uniform concentration of the free fatty acid over anextended period of cooking.

After the cereal product has been submerged in the cooking oil for apredetermined time such as from about to about 50 seconds depending uponthe product and other factors, the product is then discharged from thefrying container 21.. The fried product carries a great deal of thecooking oil from the container 21 as previously noted. This friedproduct is then discharged for packaging or for subsequent treatment ifadditional qualities need be intnoduced into the product. The aboveprocess may be carried out under somewhat different conditions byutilizing for instance a cereal product composed primarily of corn. Thecorn or the corn product may be fed in a pellet form into thecirculating oil where it is fried at a temperature of from about 380 F.to about 405 F. With these temperatures, a frying time of about 6 to 12seconds produces a uniform, palatable product of high quality. Any ofthe oils or frying materials normally used in a deep fat fryer may beused in this continuous process for frying the product; safflower oil,corn oil and coconut oil have been found to work quite well.

In a preferred embodiment, the above listed product is submerged in oilsuch as safllower oil which has been heated to a temperature of about395 F. With these conditions it has been found that a frying time ofabout 8 seconds produces a high quality product. The product isuniformly cooked and is crisp and flavorful. Again note that the productcould be simply fed into the heated oil, however, complete submersion ofthe product in the oil is again preferred in order to maintain a highuniformity of cooking of the product. This product tends to float on thesurface of the cooking oil and submersion of the product during thecooking time of 8 seconds results in a higher overall quality of thecooked product.

It should be noted that the above process can be carried out by simplyreplacing the cooking oil each time a batch of the product is cooked. Inso doing the free fatty acid concentration of the oil which influencesthe flavor of the finished product could be maintained at a very lowlevel very near the value of .03% or less of free fatty acid which ischaracteristic of new oil. However,

the process may also be carried out in the above described apparatuswherein the free fatty acid concentration of the oil is maintained atthe very low and constant level of about .07% free fatty acid (see curve174 of FIGURE 11). Use of the above described apparatus permitscontinuous cooking of a vast quantity of the product and results in ahigh quality product. The temperatures needed for the frying operationcan be maintained for extended periods of time to insure that noundercooked or overcooked product results.

It is to be understood that the above described arrangements ofapparatus and arrangements of process steps are simply illustrative ofthe application of the principles of the invention. Numerous otherarrangements may be readily devised by those skilled in the art whichwill embody the principles of the invention and fall within the spiritand scope thereof.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A deep fat fryer apparatus for cooking food products in a cooking oilwhich comprises a container for hot cooking oil; buckets for carryingthe products to be cooked; means for moving the buckets relative to saidcontainer through an operational cycle of constant duration wherein saidbuckets are successively charged with products, submerged in the cookingoil, and purged of the products; means for purging said bucket of saidproducts; means for charging said buckets with the products; a poweroperated timing device interconnecting said means for charging, saidmeans for :purging, and said means for moving to effectuate theoperational cycle and to drive said means for moving; a heater remotelylocated with respect to said container for heating said oil; and acirculatory system for continuously circulating the heated oil betweensaid heater and said container.

2. An apparatus in accordance with claim 1 which further includes asurge tank in said circulatory system, a source of -oil for replenishingthe oil in said system, a solenoid operated valve interconnecting saidsource and said surge tank, and means responsive to the oil level insaid surge tank for actuating said valve to direct cold oil from saidsource to said surge tank.

3. An apparatus in accordance with claim 2 which further includes a flowmeter in said circulatory system for sensing the rate of oil flow insaid system and a valve means responsive to said flow meter forregulating the rate of flow of oil in said system.

References Cited by the Examiner UNITED STATES PATENTS 1,630,676 5/1927Smith 99-404 1,961,532 6/1934 Synder 99-354 1,993,609 3/1935 Kennedy99-404 X 2,106,156 1/1938 Munro.

L l 12,309 3/1938 Santillan 99-400 X 2,253,567 8/1941 Kochenour et al.99-404 2,616,359 11/1952 Pierson 99-404 2,807,203 9/1957 Buechele et al99-404 2,997,190 8/1961 Reed 214-59 X 3,022,722 2/1962 Arvan 99-4043,036,513 5/1962 Reeves 99-404 WALTER A. SCHEEL, Primary Examiner.

BILLY J. WILHITE, Examiner.

1. A DEEP FAT FRYER APPARATUS FOR COOKING FOOD PRODUCTS IN A COOKING OILWHICH COMPRISES A CONTAINER FOR HOT COOKING OIL; BUCKETS FOR CARRYINGTHE PRODUCTS TO BE COOKED; MEANS FOR MOVING THE BUCKETS RELATIVE TO SAIDCONTAINER THROUGH AN OPERATIONAL CYCLE OF CONSTANT DURATION WHEREIN SAIDBUCKETS ARE SUCCESSIVELY CHARGED WITH PRODUCTS, SUBMERGED IN THE COOKINGOIL, AND PURGED OF THE PRODUCTS; MEANS FOR PURGING SAID BUCKETS OF SAIDPRODUCTS; MEANS FOR CHARGING SAID BUCKETS WITH THE PRODUCTS; A POWEROPERATED TIMING DEVICE INTERCONNECTING SAID MEANS FOR CHARGING, SAIDMEANS FOR PURGING, AND SAID MEANS FOR MOVING TO EFFECTUATE THEOPERATIONAL CYCLE AND TO DRIVE SAID MEANS FOR MOVING; A HEATER REMOTELYLOCATED WITH RESPECT TO SAID CONTAINER FOR HEATING SAID OIL; AND ACIRCULATORY SYSTEM FOR CONTINUOUSLY CIRCULATING THE HEATED OIL BETWEENSAID HEATER AND SAID CONTAINER.